A muscular driven one-man boat is known from the patent U.S. Pat. No. 5,429,064. The boat has two treadles that can be turned on an axis that are moved reciprocally up and down by the person. A chamber located under each treadle is connected with the surface of the water by an inlet valve and an outlet valve. During the downward movement of the treadle, the inlet valve is closed and the outlet valve is open so that the water located in the chamber is conveyed outwards through the outlet valve. During the upward movement of the treadle, the inlet valve is open and the outlet valve is closed so that the chamber is again filled with water. Therefore, with the alternating upward and downward movement of the treadles one chamber is always filled with water and the other is simultaneously emptied. This leads to rocking movements of the boat that run transversely to the travel direction.
The object of the invention is to develop a water sport device with better driving properties.